Enhancement of Activity Stability of Electrocatalysts with Hybrid Support of Ordered Mesoporous Carbon and SiC for Oxygen Reduction Reaction

Tuesday, 3 October 2017
Prince George's Exhibit Hall D/E (Gaylord National Resort and Convention Center)
C. Pak (Gwangju Institute of Science and Technology), D. J. You (Department of Chemistry, Sungkyunkwan University), S. W. Lee (GET, SIT, IIT, Gwangju Institute of Science and Technology), D. H. Kim (Gwangju Institute of Science and Technology), B. H. Lee (GET, SIT, IIT, Gwangju Institute of Science and Technology), and J. M. Kim (Department of Chemistry, Sungkyunkwan University)
Recently, the polymer electrolyte membrane fuel cell (PEMFC) is attracted the attention as an environment-friendly powertrain for the fuel cell electric vehicle(FCEV) and a residential combined heat and power system since this system has the advantages such as zero-emission of harmful gas, high energy efficiency and relatively low operating temperature for ambient starting. For the past decades, there many progress in the materials and system control methods to enhance the durability of catalyst [1,2]. However, the insufficient durability of supported catalysts among the major obstacles of the PEMFC should be overcome for expanding the practical market [2].

Supported catalysts for the cathode are usually composed of carbon support and catalytically active elements such as Pt, Pd, Ru. During the operation of PEMFC, corrosion of carbon support such as carbon black and activated carbon is one of the main causes of the performance degradation, which results in the loss of surface areas of active metals by detachment and agglomeration [3,4]. Although non-carbon supports have been developed to replace the carbon support for a long time, the challenges like large surface area, high electrical conductivity, and appropriate water management are remained [5]. Thus, more durable novel carbon support under the operating conditions of PEMFC is required.

The ordered mesoporous carbon (OMC), which have a large surface area and very well-connected the mesopores has been developed as a novel support for the fuel cell applications [6,7]. For example, Pt supported on the S-containing OMC(S-OMC) showed a higher thermal stability compared to the carbon black and pure OMC due to the strong metal-support interaction [7]. However, the mesopore structure of OMC support disappeared after 2000th voltage cycling test. Therefore, structural reinforcement for the OMC support is needed to improve the electrochemical stability [8].

In this presentation, we would like to show a unique hybrid support consisting OMC and SiC on the surface of carbon nanorod of OMC to enhance the stability of catalytic stability of the supported catalyst using the hybrid support for oxygen reduction reaction (ORR). The hybrid support is prepared by changing the temperature for the carbothermal reduction process during the nano-template method [9]. The temperature was carefully controlled in the range of 1600 to 1800 K, respectively to generate SiC on the carbon nanorod for hybrid support with high surface area and interconnected mesopore structure. The SiC contents in the hybrid support were increased by increasing the carbothermal temperature from ca. 10wt% to 51wt%. The Pt catalyst supported on the hybrid support showed excellent activity stability for ORR compared to the Pt particles on the pristine OMC and commercial Pt/C catalyst. The activity for the ORR of Pt on the hybrid support having ca. 10wt% SiC is maintained more than 99% after 1000 cycles between 0.6 and 1.4 V at 50mV/s. In addition, the effect of SiC content and carbon source for OMC on the structural stability of the hybrid support will be discussed.

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